1. I. M. Gelfand and B. M. Levitan, Dokl. Akad. Nauk SSSR 77, 557 (1951); Izv. Akad. Nauk SSSR, Ser. Mat. 15, 309 (1951).
2. V. A. Marchenko, Dokl. Akad. Nauk SSSR 104, 695 (1955).
3. M. G. Krein, Dokl. Akad. Nauk SSSR 76, 21 (1951); 76, 345 (1951).
4. K. Chadan and P. C. Sabatier, Inverse Problems in Quantum Scattering Theory (Springer-Verlag, New York, 1977; Mir,Moscow, 1980).
5. B. N. Zakhar’ev and A. A. Suz’ko, Direct and Inverse Problems: Potentials in Quantum Scattering, 2nd ed. (Énergoatomizdat, Moscow, 1985; Springer-Verlag, Berlin, 1990).